Bent tip composite golf shaft

ABSTRACT

Apparatus for making a golf club shaft with a bent angular tip using a straight and non-flexible main shaft body mandrel and a secondary tip mandrel disposed at an angle therewith.

RELATED APPLICATIONS

[0001] The present invention is a continuation-in-part of U.S. patentapplication Ser. No. 09/436,242, filed Nov. 9, 1999 titled BENT TIPCOMPOSITE GOLF SHAFT.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to composite golf shafts and inparticular to a combination of methods for molding the tip of a golfshaft at a precise angle.

[0003] Traditionally golf club shafts have been made straight taperingfrom a butt section to a narrower tip section which is inserted into thehosel of a golf club head. Typically the butt section includes a grip toenable a golfer to swing the golf club. With the advent of sophisticatedmolding techniques, it is no longer necessary for the golf club shaft tobe at a straight angle. For example, it is well known for putters tohave the tip portion of the shaft bent at a precise angle in order toposition a golfers hands in a desired location. Similarly, in my U.S.Pat. No. 5,931,741, a hosel-less golf club is disclosed using a singlebent shaft, the bend being such that the shaft may enter the club faceat various locations and vary between a minimum of five degrees to amaximum of 180 degrees depending in part upon the loft angle of the golfclub head.

[0004] Other patents of interest are U.S. Pat. Nos. 3,166,320 to Onionsand 5,255,914 to Schroder, both of which show a wood type golf club headwith a hosel and having a bent steel shaft tip which is angularly offsetfrom the main elongated shaft portion of the club.

[0005] U.S. Pat. No. 5,384,085 to Houser et al relates to a method ofmaking a bent graphite golf shaft using a mandrel which is flexible overits entire length. Col 9, lines 12 and 13.

[0006] U.S. Pat. No. 5,465,959 to Cheng relates to a golf club shaftmade of a composite material such as carbon graphite fiber and having abent front section connected to a bent shaft section using a uniformdiameter link to couple the parts together. The bent section is formedby wrapping a core with carbon fiber fabric and then thermally pressingit to form the desired shape.

[0007] U.S. Pat. No. 5,409,220 to Lombardo shows a putter type golf clubhead having a bent shaft with the tip offset approximately 20 degreesfrom the main portion of the shaft. The patent discloses the shaft asbeing a metal tube substantially hollow between its ends.

SUMMARY OF THE INVENTION

[0008] The present invention relates to a carbon fiber graphitecomposite shaft having a bent tip and to a method of making the same.Carbon fiber graphite composite golf shafts are known to be manufacturedusing a variety of fibers including carbon fiber, fiberglass, Kevlar andthe like with carbon fiber being the predominate fiber used. Thematerial is commonly called prepreg or prepreg composite. In a preferredembodiment of manufacturing a bent composite shaft for golf clubs, amold is fabricated having dimensions specified by the size of the shaft.Two mandrels, a tip mandrel and a main body mandrel, are used with aconventional bladder. The tip mandrel is inserted into the tip end ofthe bladder at the desired angle, and the main body mandrel is insertedinto the opposite end of the bladder, allowing approximately a two inchgap separating the two mandrels inside the bladder at the point wherethe angle is to be molded in the shaft. The prepreg composite materialis then wrapped over the entire bladder and mandrel assembly. Thematerial wrapped over the bend angle area preferably is an intermediatemodulus high strain prepreg material or other high strain material suchas glass fiber for added strength in this section where additionalstresses will occur when a golf ball is struck. All of the wrappedassembly is placed in the mold and compression molded to 300 degreesFahrenheit for 7-10 minutes or up to 2.5 hours at 250 degrees F. Theformed shaft is removed from the press and the mandrels removed. Theshaft surface is prepared for finishing, light sanding or other abrasivetreatments, as required. Additionally paint may be applied.

[0009] An alternate method of producing a composite bent shaft uses asingle long one piece flexible mandrel which may be made of flexiblesilicone or rubberized material, flexible wound spiral metal or flexiblesolid metal. Alternately the above two methods may eliminate the use ofan intermediate bladder. When the bladder is not used, the prepregmaterial is wrapped directly over the mandrels. A mandrel puller will berequired to assist in removing mandrels if a bladder is not used.

[0010] Still another method contemplates using a permanent elbowconnection such as a plastic or rubberized piece that would fit betweenthe two separate tip and main body mandrels which fills the gap betweenthe two mandrels. This elbow connection used without a bladder,permanently remains inside the shaft after the mandrels are removed.

[0011] Still other alternate methods includes a mechanical connectionbetween the two mandrels including a screw or mortise and tenonconnection for holding the mandrels together.

[0012] Still another method is to butt the two ends of the two mandrelsup against each other at the desired angle.

[0013] Still another method uses a scrim wrap to connect a solid orflexible tip mandrel to a main body mandrel.

[0014] An object of the present invention is the provision of acomposite golf club shaft having a bent or angular tip section andmethods of making the same.

[0015] Other objects and advantages of the present invention will becomeapparent from the following detailed description when viewed inconjunction with the accompanying drawings, which set forth certainembodiments of the invention

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a sectional view of a first embodiment of the presentinvention.

[0017]FIG. 2 is a sectional view of a second embodiment of the presentinvention.

[0018]FIG. 3 is a sectional view of a third embodiment of the presentinvention.

[0019]FIG. 4 is a sectional view of a fourth embodiment of the presentinvention.

[0020]FIG. 5 is a sectional view of a fifth embodiment of the presentinvention.

[0021]FIG. 6 is a sectional view of a sixth embodiment of the presentinvention.

[0022]FIG. 7 is a sectional view of a seventh embodiment of the presentinvention.

[0023]FIG. 8 is a sectional view of a eighth embodiment of the presentinvention.

[0024]FIG. 9 is a sectional view of a ninth embodiment of the presentinvention.

[0025]FIG. 10 is a sectional view of a tenth embodiment of the presentinvention.

[0026]FIG. 11 is a sectional view of a eleventh embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0027] The detailed embodiments of the present invention are disclosedherein. It should be understood, however, that the disclosed embodimentsare merely exemplary of the invention, which maybe embodied in variousforms. Therefore, the details disclosed herein are not to be interpretedas limited, but merely as the basis for the claims and as a basis forteaching one skilled in the art how to make and/or use the invention.

[0028] The present invention is directed to golf club shafts having abent tip structure of the type disclosed in my U.S. Pat. No. 5,931,741for a hosel-less golf club with a single bent shaft. The patentdescribes a golf club where in a golf club shaft is bent so as to bedirectly inserted into the ball striking face adjacent to heel of thegolf club head to totally eliminate the need for a shaft hosel. Theshaft enters the club face at various locations and the bend of theshaft may vary between a minimum of five degrees to a maximum of 180degrees depending upon the loft angle of the particular club head. Thepresent invention describes a number of methods and structures usedtherewith for producing golf club shafts of composite or graphitematerial suitable for use with the golf club described in the abovepatent.

[0029] In a preferred method for making a golf club shaft, a mold isformed sized to the length and outside diameter of the shaft dimensions.It will be appreciated that the butt end of a shaft generally has agreater diameter and gradually tapers toward the tip. In a preferredmethod, composite prepreg material is wrapped around an inner mandrel,which may or may not include an inner bladder. The wrapped mandrel isplaced in the mold and the shaft is cured under suitable heat andpressure. Once the shaft materials are cured, the mandrel is removed andthe shaft is then finished by sanding, coating, painting or the like. Itwill be appreciated that the present invention is equally applicablewith various shaft fibers including carbon graphite, Kevlar, fibreglass,and similar materials with a thermoset or thermoplastic resin matrix andmay use well known manufacturing methods such as the lay up method,balloon molding, filament winding, autoclave molding, compressionmolding and the like. The shaft fibers may be oriented in a variety ofangular configurations depending upon the shaft characteristics sought.

[0030] In producing composite single bent graphite shafts in accordancewith the present invention preferably the overall length of the finishedshaft would be approximately 44 inches with a weight of 75 grams, forexample. The tip end would be made stiffer and formed preferably with anoutside diameter in the range of 0.335 or greater inches and disposed ata tip angle of approximately 20 degrees. The butt end has a outsidediameter of approximately 0.60 inches with the outside diameter of theshaft gradually tapering between the smaller tip section to the largerbutt section. However, it will be appreciated that the present inventionis equally applicable to golf club shafts which do not gradually taperbut include various configurations such as bulges, parallel sections,reduced radiuses and so forth.

[0031] Referring to FIG. 1, a mandrel assembly 10 for making a compositegraphite shaft with a bent tip is shown including a tip mandrel 12 amain shaft body mandrel 14 and a covering bladder 16. A gap 18 existsbetween the tip mandrel 12 and the main shaft body mandrel 14 with noconnection therebetween. This enables the tip mandrel 12 to be placed ata desired angle with the main shaft body mandrel 14. In this embodimentthe main shaft body mandrel 14 is straight and non-flexible and made ofsolid steel. The tip mandrel 12 is shown as straight and non-flexiblesolid steel, but it maybe flexible metal or even a flexible silicone orrubberized material. It will be appreciated that the mandrel assembly 10is wrapped with prepreg material 17 which actually forms a shaft duringthe curing process. The material is formed in a mold and cured asdescribed hereinabove in the background of the invention. When the cureis finished, the tip mandrel 12 and the shaft mandrel 14 may bewithdrawn from opposite ends of the completed shaft having a bent tip.

[0032]FIG. 2 illustrates a unitized, one piece mandrel 20 made ofsilicone rubberized material having a non-flexible, main body section 22and a flexible, bent tip section 24 to form the desired shaftconfiguration. In this embodiment the mandrel 20 is removed by pullingit out of the butt end of the cured shaft. The flexibility of themandrel allows the tip section 24 to straighten as pulling pressure isapplied and be easily removed.

[0033]FIG. 3 illustrates a mandrel assembly 30 in accordance withpresent invention using a straight and non-flexible tip mandrel 32, astraight and non-flexible main shaft body mandrel 34 and a shapedpermanent elbow 36. In this embodiment the permanent elbow 36 preferablyis made of a rubber or plastic material and inserted between a steel tipmandrel 32 and steel main shaft body mandrel 34. After mandrels 32 and34 are wrapped with prepreg composite material 38 and cured the mandrels32 and 34 are removed leaving the permanent elbow 36 in place to add tothe rigidity of the shaft at the point of the bend.

[0034]FIG. 4 shows another variation of a mandrel assembly 40 includinga straight and non-flexible main shaft body mandrel 42 of steel, aflexible tip mandrel 44 which may be silicone or rubberized material,flexible solid metal or flexible wound spiral metal. In this embodimenta scrim wrap 46 is provided over the ends of each mandrel 42 and 44forming a connection therebetween. The assembly may be covered with abladder, and wrapped with prepreg material and cured as with previousembodiments. The mandrels 42 and 44 are removed from the shaft after itis cured.

[0035]FIG. 5 illustrates still another mandrel assembly 50 using astraight and non-flexible steel main shaft body mandrel 52 and a tipmandrel 54 of solid flexible metal. The inner ends of the mandrel 52 andthe mandrel 54 abut each other and then may be covered with a bladderwrapped with prepreg material and cured to form a bent tip shaft.

[0036]FIG. 6 shows yet another embodiment of a mandrel assembly 60 usinga straight and non-flexible steel main body mandrel 62 and a flexibletip mandrel 64 which uses a connector screw 66 to make a solidconnection between the mandrels. As with the previous embodiment themandrels may be covered with a bladder, wrapped and cured.

[0037]FIG. 7 illustrates a further embodiment of a mandrel assembly 70including a straight and non-flexible main shaft body mandrel 72 andflexible mandrel 74 wherein the tip of the main body mandrel 72 and theadjoining tip of the flexible mandrel 74 are connected by a mortise andtenon joint 76. The assembly may include a bladder which is wrapped byprepreg and cured.

[0038]FIG. 8 shows an embodiment of a mandrel assembly 80 including astraight and non-flexible, solid main shaft body mandrel 82 and aflexible wound spiral metal tip 84. The assembly 80 may be covered witha bladder wrapped and cured. It will be appreciated that the flexiblewound spiral metal tip 84 may be used with and without a connection tothe main shaft mandrel 82 including a gap, a butt against connection, ascrew connection, a scrim wrap connection or a mortise and tenonconnection of the type described hereinabove.

[0039]FIG. 9 shows another embodiment of a mandrel assembly 90 using astraight and non-flexible main body mandrel 92 and a flexible tipmandrel 94 made of silicone rubberized material. The ends of eachmandrel 92 and 94 abut against each other and may be wrapped with abladder.

[0040]FIG. 10 illustrates a mandrel assembly 100 using a single solidmetal, flexible, rod bent into a straight and non-flexible main bodymandrel 102 and a flexible tip mandrel 104. It will be appreciated thatthe flexible metal mandrel is bent to form a bent tip shaft.

[0041]FIG. 11 shows a mandrel assembly 110 using a single piece of woundspiral metal to form a main body mandrel 112 and tip mandrel 114.

[0042] It will be appreciated that when a bladder assembly is used inany of the above described embodiments, the prepreg material is wrappedover the bladder before being placed in a mold and cured. If a bladderis not used, the prepreg material is wrapped directly over the mandrelbefore being placed in a mold and cured.

[0043] While various preferred embodiments have been shown anddescribed, it will be understood that there is no intent to limit theinvention by such disclosure, but rather, is intended to cover allmodifications and alternate constructions falling within the spirit andscope of the invention as defined in the appended claims.

1. Apparatus for molding a rigid, composite golf club shaft with a benttip comprising: a two-part mandrel sized to the length of a conventionalgolf club shaft, for molding a rigid, composite golf club shaft with abent tip said mandrel having two separate sections of elongatedmaterial; a first of said sections being further defined as a firststraight, non-flexible main body section and a second of said sectionsbeing a straight non-flexible tip section, said tip section able to bedisposed at a pre-selected angle with respect to said main body section.2. Apparatus for molding a rigid, composite golf club shaft with a benttip comprising: a two-part mandrel being sized to the length of aconventional golf club shaft, for molding a rigid, composite golf clubshaft with a bent tip; said mandrel having two separate mandrel sectionsof elongated material; said sections including a first straight,non-flexible main body section and a second straight, non-flexible tipsection, said sections each having non-connected ends; and a permanentelbow at the interface of and abutting said ends of said separatesections.
 3. Apparatus for molding a rigid, composite golf club shaftwith a bent tip comprising: a mandrel sized to the length of aconventional golf club shaft, for molding a rigid, composite golf clubshaft with a bent tip; said mandrel having a straight and non-flexiblemain body section and a flexible tip section; said mandrel being formedof a one-piece, unitized, elongated solid bar of material; said flexibletip section being able to be disposed at a pre-selected angle withrespect to said main body section.
 4. The apparatus of claim 3 whereinsaid solid bar of material is metal.
 5. The apparatus of claim 3 whereinsaid solid bar of material is solid, non-hollow rubberized silicone. 6.The apparatus of claim 1 wherein said main body mandrel is metal andsaid tip mandrel is metal.
 7. Apparatus for molding a rigid, compositegolf club shaft with a bent tip comprising: a two-part mandrel sized tothe length of a conventional golf club shaft, for molding a rigid,composite golf club shaft with a bent tip; said two-part mandrel havingtwo separate sections, including a straight and non-flexible main bodymandrel and a flexible tip mandrel; said main body mandrel being metaland said tip mandrel being solid, non-hollow rubberized silicone; saidmain body mandrel and said tip mandrel having non-connecting ends inabutment to each other, said flexible tip section being able to bedisposed at a pre-selected angle with respect to said main body mandrel.8. Apparatus for molding a rigid, composite golf club shaft with a benttip comprising: a two-part mandrel sized to the length of a conventionalgolf club shaft; said two-part mandrel having two separate sections,including a straight and non-flexible main body mandrel and a flexibletip mandrel; said main body mandrel being metal and said tip mandrelbeing flexible metal; said main body mandrel and said tip mandrel havingnon-connecting ends in abutment to each other; said flexible tip sectionbeing able to be disposed at a pre-selected angle with respect to saidmain body mandrel.
 9. Apparatus for molding a rigid, composite golf clubshaft with a bent tip comprising: a two-part mandrel sized to the lengthof a conventional golf club shaft for molding a rigid, composite golfclub shaft; said two-part mandrel including a straight and non-flexiblemain body mandrel and a flexible tip mandrel; said main body mandrel andsaid tip mandrel being formed of two separate sections of elongatedmaterial and further including a scrim wrap overlapping said main bodymandrel and said tip mandrel; said main body mandrel and said tipmandrel having non-connecting ends in abutment to each other; saidflexible tip section being able to be disposed at a pre-selected anglewith respect to said main body mandrel.